Polymer for chemically amplified resist and a resist composition using the same

ABSTRACT

The present invention relates to a polymer for a chemically amplified resist and a resist composition using the same. The present invention provides a polymer represented by the Formula (1) and a chemically resist composition for extreme ultraviolet light comprising the same. The chemically amplified resist composition comprising the polymer represented by the formula (1) of the present invention responds to mono wavelength in a micro-lithography process and can embody a micro-pattern of high resolution on a substrate.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a polymer for a chemically amplifiedresist and a resist composition comprising the same More particularly,the present invention relates to a novel polymer that can be used for achemically amplified resist composition that can form finer patterns ona substrate in a micro-lithography process suitable for micro-processingof semiconductors, using a mono wavelength as the light source for lightexposure, and which improves post exposure delay (PED) stability and hashigh resistance against the heat produced by dry etching, and a resistcomposition using the same.

(b) Description of the Related Art

The resist composition is generally used in the preparations of largesize integrated circuits (LSI) or in high resolution lithography.Recently, resist compositions with high resolution and high sensitivityhave been required due to the densification of large size integratedcircuits. Such embodiments of microcircuits in semiconductor integratedcircuits generally proceed using a lithography process through whichprocess the microcircuit is constructed by coating resist on asubstrate, transcribing patterns on the substrate using a prepared photomask, and etching the substrate along the transcribed pattern.

Such lithography processes comprise the following steps: (a) a coatingstep comprising uniformly coating resist on the surface of a substrate,(b) a soft baking step comprising evaporating the solvent from thecoated resist film to adhere the resist film to the surface of thesubstrate, (c) a light exposure step comprising light exposing thesubstrate while projecting the circuit pattern on the mask, repeatedlyand sequentially using a light source such as ultraviolet light totranscribe the pattern of the mask onto the substrate, (d) a developmentstep comprising selectively removing the part in which chemicalproperties such as solubility change by the exposure to the light sourceusing development liquid, (e) a hard baking step for adhering morefirmly the resist film that remains on the substrate after development,(f) an etching step comprising etching the predetermined part along thepattern on the developed substrate in order to impart the electricproperties and (g) a stripping step comprising removing the resist thatbecomes unnecessary after said etching step.

The speed of high-integration of semiconductor integrated circuits hasincreased 4-fold for 3 years. Thus, at present, in the field of dynamicrandom access memory (DRAM), 64 mega bit DRAM and 256 mega bit DRAM aremass-produced, and the development of giga bit DRAM has started.

The conventional 16 mega DRAM used the technology of a 0.5 μm circuitline, while 64 mega DRAM uses the technology of a circuit line of 0.3 μmor less, and 256 mega DRAM and giga DRAM requires an ultra micro patternof less than quarter micro, such as 0.20 μm, 0.18 μm, 0.15 μm dependingon the design. In such micro-processing, the light-radiation wavelengthmoves to extreme ultraviolet. Therefore, there is a need for thedevelopment of a new resist that can effectively respond to extremeultraviolet light.

The resist of the prior art comprising quinonediazide photoactivematerial and phenol novolac resin cannot satisfy the above-mentionedrequirement, because, in such a resist system, there is a largeabsorption at the wavelength zone of 300 nm or less and thus, when monowavelength light-exposure of 300 nm or less is conducted, patternprofile is significantly deteriorated. Therefore, there is a need forthe embodiment of a stiff pattern in which the pattern profile does notflow.

In order to embody such a pattern profile, an aligner commonly called astepper is generally used as a light-exposing apparatus. Suchlight-exposing apparatuses are divided into an apparatus using G line(wavelength 436 nm), I line (wavelength 365 nm) of mercury light, and anapparatus using an excimer laser of mono wavelength KrF (248 nm) and ArF(193 nm) according to the light source. For embodying micro-patterns onthe substrate, the resolution value should be small The resolution valueis expressed by the following Rayleigh diffraction limiting equationTheoretically, since the resolution value becomes smaller as thewavelength of the light source becomes shorter, it is preferable to usea shorter mono wavelength.

[Diffraction Limiting Equation]

R=κλ/NA

Wherein, κ is a constant, λ is a wavelength of the light used, and NA isthe number of the aperture of the lense.

In order to achieve high resolution of a quarter micron or less, thecapacity of degradation of lithography should be improved. For thispurpose, it is effective to use a mono wavelength light source having ashort wavelength and to increase the aperture number (NA) of the opticallense of the exposing apparatus.

Accordingly, a resist composition that uses a high-output excimer laserlight source so as to respond to the high-resolution tendency ofsemiconductor integrated circuits is commonly used. This composition isfor a KrF and an ArF excimer laser, and high-sensitivity resist systemsintroducing the chemical amplification concept are suggested.

A chemically amplified resist produces acid by photolysis due to theirradiation of extreme ultraviolet light. The produced acid degrades theprotective group which is partially protected with the aid of heat, andthen it reacts with the acid labile polymer to initiate the chainreaction or act as a catalyst, and thus, one molecule of acid causes anumber of bond formation or bond degradation reactions Therefore, a term“chemical amplification” means the phenomenon whereby active speciesproduced by the action of one photon causes chemical chain reactions torapidly amplify the yield of quantum. Due to this continuous reaction ofacid, the concept of chemical amplification was introduced and used.

A chemically amplified resist is divided into a two-component systemcomprising an acid-labile polymer and a mineral acid producing agent anda three-component system comprising an acid-labile polymer, a mineralacid producing agent and a matrix resin. In the resist of the prior art,the degradation or the cross-reaction of a light sensitive materialoccurs directly at the light exposure part, and, when it is developed, aresist image pattern of a positive or negative form is obtained.However, in the chemically amplified resist, an acid labile polymer orcompound is not directly reacted by light exposure, but an acid isproduced from the mineral acid producing agent in the light-exposedpart, and only a latent image is produced The produced acid acts as acatalyst for the acid labile polymer in the post-exposure bake (PEB)step, and thus, it causes the amplification of the reaction and thesignificant difference in solubility.

The first resist based upon the chemical amplification concept was aresist using a polyhydroxystyrene derivativepoly[p-(t-butyloxycarbonyloxy)styrene] (PBOCSt) blocked with t-BOC(tertiary-butoxy carbonyl) group and onium salt as a mineral acidproducing agent, and it is described in American Chemical Society,“Polymers in Electronics”, ACS Sym Series, No. 242 by Ito et al. Thereason for using the polyhydroxystyrene derivative is as follows sincethe novolac phenol resin that was used in the resist of the prior artlargely absorbs deep UV, UV light cannot sufficiently reach the contactsurface of the resist substrate Thus, in the light-exposed part of theresist, chemical changes by light-exposure do not sufficiently occur inthe membrane thickness direction, and thus the solubility of thedeveloping liquid becomes irregular. This makes the shape of the sectionof the resist pattern formed after development triangular Thus when theobtained resist pattern is used as an inner etching mask for asubstrate, the micro-circuit pattern to be aimed cannot be transcribed.In order to compensate for this, there is a need to change the basepolymer, and a polyhydroxystyrene derivative having excellent plasmaresistance is known to be suitable.

As examples, a chemically amplified resist comprisingpoly(p-styreneoxytetrahydropyranol) and an acid producing agent is knownby Ueno et al in the 36^(th) Japanese Applied Physics Societyannouncement, 1p-k-7, 1989, and a three component system resistcomprising novolac phenol resin, bisphenol-A substituted with t-BOCgroup and pyrogallol methanesulfonic ester is known from Schlegel in the37th Japanese Applied Physics Society announcement, 28p-ZE4, 1990. Inaddition, technologies relating to the preparations of said resists aredisclosed in JP patent publication Hei 2-27660, JP patent publicationHei 5-232706, JP patent pubication Hei 5-249683, and U.S. Pat. Nos.4,491,628 and 5,310,619 However, while such chemically amplified resistshave excellent resolutions compared to the resist for g-line and I-lineof the prior art, they are likely to be affected by the surroundingenvironment, particularly by oxygen, moisture and other traceingredients around the membrane surface, and it is difficult to formstable micro patterns because a trace amount of acid is produced in thelight-exposed part.

In addition, MacDonald et al. reported in Porc. SPIE, Vol. 1466. 1991that trace dimethylaniline contained in the air decreases the activityof the acid produced around the surface of the resist by light exposure,and it produces a layer that hardly melts on the membrane surface, andsaid hardly-melting layer remains on the surface of the resist patternafter development treatment. However, this process has the problem thatfooting is caused by the reaction of the micro pattern with thesubstrate due to the time delay from the light exposure to the PEBprocess, and a T-top type pattern is produced by environmental pollutiondue to the amine ingredient distributed in the air in the process line.Therefore, there is a need for compensating the PED stability of theresist composition using said compound, and there is a need for a resistcomposition using a novel base polymer suitable to embody highsensitivity and high resolution at a wavelength of 300 μm or less.

In addition, recently, large size integrated circuit tends to use a dryetching process Said dry process is for increasing integration ofsemiconductor integrated circuit, and changes the manner of etching onthe substrate in the lithography process from wet etching having largeside etching of the prior art to dry etching having small side etching.In the dry etching process, the resist pattern should not change by theheat produced when etching. In addition, as the degree of integrationincreases, higher heat resistance is required by the resist used.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a novelpolymer that can be applied to a chemically amplified resist compositionthat can form finer patterns on a substrate in a micro lithographyprocess using extreme ultraviolet light, improves post exposure delaystability, and has high resistance against the heat produced by dryetching, and a resist composition using the same.

In order to achieve the above object, the present invention provides apolymer for a chemically amplified resist represented by the following

Formula 1

Wherein, R₁ is hydrogen or methyl R₂ is hydrogen or CH₂CH₂COOC(CH₃)₃, R₃is chloro, bromo, hydroxy, cyano, t-butoxy, CH₂NH₂, CONH₂, CH═NH,CH(OH)NH₂ or C(OH)═NH,

x+y+z=1, x is 0.1-0.9, y is 0.01-0.89, z is 0.01-0.89, and

n is 1 or 2, and when n is 2, both R₂ are the same.

In addition, the present invention provides a resist compositioncomprising (a) a polymer represented by the formula 1, (b) an acidproducing agent and (c) an organic solvent.

DETAILED DESCRIPTION AND THE PREFERRED EMBODIMENTS

The present invention will now be explained in more detail.

In order to synthesize a polymer capable of being alkali developedrepresented by the formula 1, three monomers constituting a polymer areprepared and they are introduced in a reactor equipped with a refluxcooler under a nitrogen environment and are reacted. Tetrahydrofuran(THF), toluene, benzene, chloroform, carbon tetrachloride, etc. can beused as a polymerization solvent. Azobisisobutyronitrile (AIBN) orbenzoperoxide (BPO) can be used as a polymerization initiator. Saidpolymerization solvent and initiator are added to the reactor andreacted while being stirred. After the reaction completes, thesynthesized polymer is precipitated in hexane to obtain precipitates,and then the precipitates rinsed several times and vacuum dried toobtain the polymer.

For synthesizing the monomer having a Z repeat unit of the compound ofFormula 1, the synthesis of cyanoalkylstyrene by way of Equation 1should be preceded. To the synthesized 4-cyanoalkylstyrene, t-butylacrylate and t-butyl methacrylate groups are added, and the preparedmonomers are stirred with other monomers such as acetoxystyrene,t-butylacrylate and t-butyl methacrylate to prepare the polymer.

The process for synthesizing the monomer having a Z repeat unitcomprises two steps. First, group I cyanide comprising sodium cyanideand potassium cyanide is mixed with alkyl alcohol comprising water andethanol, as shown in Equation 1. To said solution, alkyl styrenecomprising 4-chloroalkylstyrene and halogen atoms is slowly introducedand is reacted to synthesize cyanoalkylstyrene. Then, the monomerobtained in Equation 1 is stirred with t-butylacrylate to synthesize4-(3-cyano-di-1,5-t-butoxycarbonyl-pentyl)styrene (CBCPS) as shown inEquation 2. Wherein, cyanoalkylstyrene and triton non-solution ortetraalkylaminehydroxide solution are dissolved in dioxane, and then,t-butylacrylate is introduced and stirred After the reaction completes,said mixture is neutralized with an acidic solution and is extracted tosynthesize CBCPS.

For the synthesis of the polymer of the present invention, THF, toluene,benzene, chloroform or carbon tetrachloride can be used aspolymerization solvent 4-acetoxystyrene or 4-butoxystyrene is added tothe prepared CPCBS with 4-butylacrylate or 4-butylmethacrylate, and thepolymerization initiator such as AIBN and BPO is added and the mixtureis stirred to prepare a polymer Said polymer has a weight averagemolecular weight (Mw) of 3,000-30,000, and the degree of dispersion canbe controlled from 101 to 300 depending on the synthetic process

The substitute monomer used in the present invention exhibits sufficientdevelopment inhibiting capacity at the non-light-exposed part, and thesubstitute group is degraded by the action of acid and is dissolved indeveloping liquid at the light-exposed part.

The resist composition using the polymer of the present inventioncomprises (a) a polymer represented by the formula 1, (b) an acidproducing agent and (c) an organic solvent.

The resist composition using the polymer of the present inventionpreferably comprises 1-50 wt % of said polymer.

As the acid producing agent, sulfonium salt, an onium salt such asiodonium, N-iminosulfonate, disulfone, bisarylsulfonyidiazomethane andarylcarbonylarylsulfonyldiazomethane can be used. Preferably, the acidproducing agent is contained in the resist composition in an amount of0.1 to 50 wt %.

The examples of sulfonium salt include the following compounds but arenot limited to them

The example of onium salt include the following compounds.

The examples of N-iminosulfonates include the following compounds.

The examples of disulfones include the following compound.

(Wherein R is H, —CH₃ or —C(CH₃)₃.)

The examples of bisarylsulfonyldiazomethanes include the followingcompound.

(Wherein R is H, —CH₃ or —C(CH₃)₃.)

The examples of arylcarbonylarylsuffonyldiazomethanes include thefollowing compound.

(Wherein R is H, —CH₃ or —C(CH₃)₃)

The organic solvent is preferably selected from the group consisting ofethyleneglycol monoethylether acetate, propyleneglycol monomethyletheracetate, ethylether acetate n-butyl acetate, methyl isobutyl ketoneethyl lactate, 3-ethoxy-ethylpropionate, 3-methoxy-methylpropionate,diglycol monoethylether, 2-heptanone, diacetone alcohol,β-methoxyisobutyric acid methylester, propyleneglycol monoethylether,propyleneglycol monomethylpropionate, methyl lactate, butyl lactate,ethyl pyruvate, γ-butyrol lactone, and a mixture thereof Preferably, theorganic solvent is contained in the resist composition in an amount of01 to 99 wt %.

The resist composition using the polymer of the present invention maycomprise a dissolution inhibitor in order to improve the dissolutioninhibition of the non-light-exposed part The use of the dissolutioninhibitor makes the difference of solubility of the light-exposed partand non-light-exposed part larger and contributes to the improvement ofcontrast. Such dissolution inhibiting additives can be added in theresist composition in an amount of 0.1 to 50 wt % based on the weight ofthe polymer of the present invention.

The examples of the dissolution inhibitor include the followingcompounds but are not limited to them.

(Wherein R is a molecule comprising C₁-C₁₀ and H and O)

The resist composition using the polymer of the present invention can beapplied as follows to obtain a micro-pattern

When the resist composition using the polymer of the present inventionis formed as a thin layer on a substrate such as a silicone wafer and istreated with a base aqueous solution, the dissolution does not occurbecause the solubility of the copolymer is low. However, when extremeultraviolet light is radiated, the resist responds and the acidproducing agent in the resist produces acid, and the developmentinhibiting substituent causes the degradation of the polymer structureby the action of heat addition in the light-exposed part and the acid isproduced again. Consequently, one acid that was produced causes chemicalamplification which causes a plurality of acid active degradation. As aresult, the solubility of the polymer largely increases in thelight-exposed part, and, when developing with the base aqueous solution,the difference in the solubilities of the light exposed part andnon-exposed part appears Thus, a resist composition having excellentresolution compared to the resist composition using G-rays and I-rays ofthe prior art can be obtained

The present invention will be explained in more detail with reference tothe following Examples and Comparative Examples However these are toillustrate the present invention, and the present invention is notlimited to them.

The Synthesis of Polymer The synthesis of 4-cyanomethylstyrene(CyMS)

In a 500 μl 4-opening flask equipped with a stirring bar, 49.01 g ofsodium cyanide was mixed with 70.07 g of water and 50.96 g of ethanol.Then, the temperature of the flask was elevated to 60° C. and the sodiumcyanide was completely dissolved. To said solution, 87.50 g of4-chloromethylstyrene was slowly added and it was reacted for 3 hourswhile stirring and maintaining the reaction temperature within 60-70° C.When the reaction terminated, said solution was cooled to 40° C., and100 g of diethylether was added and the diethylether layer wasseparated. The separated organic layer was extracted with 300 g of waterthree times, and the water layer was extracted with 50 g of diethyletherand was combined with said organic layer. The separated obtained organiclayer was dried with magnesium sulfate for one day, and then the organicsolvent was removed using an evaporator to obtain the product4-cyanomethylstyrene. The yield of the product was 80%, and the productwas a deep purple color.

Said synthesis was according to the Equation 1.

The Synthesis of 4-(3-cyano-di-1,5-t-butoxycarbonyl-pentyl)styrene(CBCPS)

In a 500 ml 4-opening flask equipped with a stirring bar, 57.28 g of4-cyanomethylstyrene prepared in the above process and 14 g of tritonnon solution were dissolved in 40 g of dioxane. 102.54 g oft-butylacrylate were slowly added to said solution for 30 minutes whilemaintaining the temperature of the reactor at 60° C., and it was reactedfor 24 hours while stirring. After the reaction, the reactant wasneutralized with a chloride solution, and the neutralized reactant wasextracted with 100 g of diethylether and 300 g of water three times, thewater layer was extracted with 50 g of diethylether and combined withthe organic layer. The separated obtained organic layer was dried withmagnesium sulfate for one day, and then the organic solvent was removedusing an evaporator. The obtained product was distillated under reducedpressure to remove unreacted material, and it was recrystallized withmethanol to obtain light yellow CBCPS in a 60% yield.

Said synthesis was according to the Equation 2.

The Synthesis of the Polymer of Formula 1

In a 500 ml 4-opening flask equipped with a temperature controllingapparatus and a nitrogen introducing apparatus, 300 ml of THF wereintroduced and nitrogen was added and it was stirred for 30 minutes. Tosaid reactor, 56.62 g of 4-acetoxystyrene, 9.16 g of t-butylacrylate and24.14 g of CBCPS prepared in the above process were introduced, 1.21 gof AIBN were added and stirred for 30 minutes under a nitrogenatmosphere while maintaining the temperature at 40° C., and thetemperature of the reactor was then elevated and the reactant wasstirred for 24 hours while refluxing. After the completion of thereaction, the temperature was lowered to room temperature and thereactant was deposited in 3 liters of hexane to obtain the precipitates.The obtained precipitates were filtered and rinsed with 2 liters ofhexane several times and were vacuum dried. The dried macromolecule wasdissolved in 300 ml of methanol in a flask, and 50 ml of 30% NH₄OHaqueous solution were added and the mixture was slowly stirred, and,after the polymer was completely dissolved, the mixture was additionallystirred for 30 minutes. The solution was deposited in 1.5 liters ofwater to obtain the precipitates, and the precipitate were filtered andrinsed with 2 liters of pure water and vacuum dried to obtain 58.23 g ofpolymer of Formula 1.

The above synthesis was according to Equation 3.

EXAMPLES 1-7 A Chemically Amplified Resist Composition

A chemically amplified resist composition was obtained by using thepolymer prepared in the above process represented by Formula 1, thecompounds represented by Formulae 2 to 6 as acid producing agents, andpropyleneglycolmonomethyletheracetate (PGMEA) and ethyl lactate (EL) assolvents in the ratios of Table 1.

Said chemically amplified resist composition was spin coated on siliconewafers at 2000 rpm and was heated to 100° C. for 90 seconds to form thinlayers with thicknesses' as described in Table 1. Micro-pattern maskswere mounted on said thin layers, mono wavelengths of 248 nm wereradiated, and said layers were heated to 110° C. for 90 seconds to causethe chemical amplification. Then, said layers were developed with atetramethylammoniumhydroxide aqueous solution for 60 seconds, and thenwere rinsed with pure water and dried to embody micro-patterns onwafers.

The relative sensitivities and resolutions of micro-patterns aredescribed in Table 1.

COMPARATIVE EXAMPLES 1-4

Chemically amplified resist compositions were prepared by usingpolyhydroxystyrene blocked with t-BOC(tertiary-butoxy carbonyl) grouprepresented by the formula 7 and EVE (ethyl vinyl ether) represented bythe formula 8 as polymers, the compounds represented by the formulae 2-6as acid producing agents, andpropyleneglycolmonomethyletheracetate(PGMEA) and ethyllactate(EL) assolvents, in the ratios of Table 1. Said compositions were spin coatedon silicone wafers and were heated to form thin layers, and werechemically amplified to embody micro-patterns, in the same manner asdescribed in the

Examples 1 to 7

The relative sensitivities and resolutions of the micro-patterns aredescribed in Table 1

TABLE 1 The composition of the resists The Acid physical property ofpattern pro- Thick- ducing ness Polymer agent Solvent of thin RelativeRes- (weight (weight (weight layer sensitivity olution part) part) part)(μm) (mj/cm²) (μm) Example Formula Formula PGMEA 0.72 31 0.18 1 1 (100)2 (5) (550) Example Formula Formula PGMEA 0.72 30 0.18 2 1 (100) 3 (5)(550) Example Formula Formula PGMEA 0.74 32 0.16 3 1 (100) 4 (2) (550)Formula 5 (2) Example Formula Formula PGMEA 0.73 31 0.16 4 1 (100) 2 (3)(250) Formula EL 5 (2) (300) Example Formula Formula PGMEA 0.72 27 0.185 1 (100) 4 (3) (550) Formula 6 (2) Example Formula Formula PGMEA 0.7128 0.20 6 1 (100) 2(3) (550) Formula 6 (2) Example Formula Formula PGMEA0.71 33 0.18 7 1 (100) 3 (3) (550) Formula 6 (2) Com- Formula FormulaPGMEA 0.73 35 0.24 parative 7 (30) 2 (5) (550) Example 1 Com- FormulaFormula PGMEA 0.73 38 0.24 parative 7 (40) 3 (5) (250) Example 2 FormulaEL 8 (60) (300) Com- Formula Formula PGMEA 0.74 39 0.30 parative 7 (100)2 (3) (550) Example 3 Formula 6 (2) Com- Formula Formula PGMEA 0.72 420.28 parative 7 (100) 3 (3) (550) Example 4 Formula 5 (2)

*The relative sensitivity in Table 1 means optimum energy (Eop).

As shown in Table 1, the resist compositions prepared in Examples 1 to 7of the present invention have resolutions of 0.16 to 0.20 μm which ismuch excellent compared to the resolutions of 0.24 to 0.30 μm of thecompositions prepared in Comparative Examples 1 to 4. In addition, therelative sensitivities of the compositions of Examples are 28 to 30mj/cm², which are excellent compared to the relative sensitivities of 35to 45 mj/cm² of the compositions of Comparative Examples.

The chemically amplified resist composition comprising the polymerrepresented by the Formula 1 can rapidly respond to mono wavelength in amicro-lithography process using extreme ultraviolet light and formmicro-patterns of high-resolution on wafers. In addition, it preventsthe modification between a resist latent image that occurs by a timedelay between light-exposure and post exposure bake resulting from theenvironmental effect and a real resist micro-circuit pattern afterdevelopment, as well as the modification of the surface layer of theresist resulting from the reaction of a mineral acid producing agent andthe acid produced by base amine, namely, the formation of T-top typepattern. The resist composition of the present invention is suitable forthe preparations of 256 mega and giga bit DRAM, because it has highresistance against the heat produced by dry etching.

What is claimed is:
 1. A polymer for a chemically amplified resistrepresented by the following Formula 1:

wherein R₁ is hydrogen or methyl, R₂ is hydrogen or CH₂CH₂COOC(CH₃)₃, R₃is Cl, Br, hydroxy, cyano, t-butoxy, CH₂NH, CONH₂, CH═NH, CH(OH)NH₂ orC(OH)═NH, x+y+z=1, x is 0.1-0.9, y is 0.01-0.89, z is 0.01-0.89, n is 1or 2, and when n is 2, both R₂ are the same.
 2. The polymer for achemically amplified resist according to claim 1, wherein said polymerhas a molecular weight of 3,000 to 30,000 and a degree of dispersion of1.01 to 3.00.
 3. A light sensitive resist composition comprising a) apolymer represented by the following formula 1:

wherein R₁ is hydrogen or methyl, R₂ is hydrogen or CH₂CH₂COOC(CH₃)₃, R₃is Cl, Br, hydroxy, cyano, t-butoxy, CH₂NH, CONH₂, CH═NH, CH(OH)NH₂ orC(OH)═NH, x+y+z=1, x is 0.1-0.9, y is 0.01-0.89, z is 0.01-0.89, n is 1or 2, and when n is 2, both R₂ are the same, b) an acid producing agent;and c) a solvent.
 4. A light sensitive resist composition according toclaim 3, wherein said polymer represented by Formula 1 is contained inthe composition in an amount of 0 1 to 50 wt %.
 5. A light sensitiveresist composition according to claim 3, wherein said b) acid producingagent is selected from the group consisting of: sulfonium salt selectedfrom:

iodonium salt selected from:

N-iminosulfonates selected from:

disulfonates which is

(wherein R is H, —CH₃ or —C(CH₃)₃) bisarylsulfonyldiazomethane which is

(wherein R is H, —CH₃ or —C(CH₃)₃) arylcarbonylarylsulfonyldiazomethanewhich is

wherein R is H, —CH₃ or —C(CH₃)₃), and a mixture thereof, and said acidproducing agent is contained in the composition in an amount of 0.1 to50 wt %.